Electronic devices with self-illuminated backlit displays have been shown to cause melatonin levels to drop, making it much harder for persons who use such devices to read or study before bedtime to fall asleep.

A group of Spanish researchers has discovered a new function of the neurotransmitter dopamine in controlling sleep regulation. Dopamine acts in the pineal gland, which is central to dictating the 'circadian rhythm' in humans—the series of biological processes that enables brain activity to adapt to the time of the day (that is, light and dark cycles).